Sequence of CX-4945 and Cisplatin Administration Determines the Effectiveness of Drug Combination and Cellular Response in Cholangiocarcinoma CellsIn Vitro

Abstract

Background: The incidence of cholangiocarcinoma (CCA) is increasing worldwide and current single chemotherapeutic drug treatments are ineffective. CX-4945 and cisplatin are currently in clinical trial for CCA treatment. Materials and Methods: We assessed the effects of the sequence of administration of CX-4945 and cisplatin applied in combination treatments on their efficacy in CCA cells in vitro. CCA cell viability was examined using 3-( 4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Apoptosis was examined using flow cytometry. The percentage of cells positive for phosphorylated H2A histone family member X (γ-H2AX) were measured using both flow cytometry and immunofluorescence. Results: CCA cell viability was reduced to 50% after 24 h of treatments with CX-4945 and cisplatin as single agents. Interestingly, treatment with cisplatin 6 h prior to CX-4945 treatment induced significantly more DNA damage and apoptosis than CX-4945 treatment followed by cisplatin. Unexpectedly, CX-4945 treatment followed by cisplatin was less effective than single treatment in RMCCA-1 CCA cells. In addition, a 1:1 ratio of each drug was the most effective combination in these cells. Conclusion: These data demonstrate that the combination of CX-4945 and cis platin acts additively when cisplatin is applied first, at least in part due to increased DNA damage and apoptosis. Furthermore, treatment with CX-4945 prior to cisplatin treatment reduces the efficacy of this drug combination in CCA cells.

A synthetic lethal dependency on casein kinase 2 in response to replication-perturbing therapeutics in RB1-deficient cancer cells

“…We chose to explore the carboplatin-sensitizing effect of the knockout of CSNK2A2 encoding the α′ catalytic subunit of the serine-threonine kinase CK2, which can be targeted with the selective inhibitor silmitasertib ( 35 , 36 ) and has a documented role in DNA damage response [reviewed in ( 37 )]. We modeled the loss of CK2 activity by knocking out catalytic subunit-encoding genes CSNK2A1 (α) and CSNK2A2 (α′).…”

A synthetic lethal dependency on casein kinase 2 in response to replication-perturbing drugs in RB1-deficient ovarian and breast cancer cells

“…We chose to explore the carboplatin-sensitizing effect of the knock-out of CSNK2A2 encoding the α’ catalytic subunit of the serine-threonine kinase CK2, which can be targeted with selective compound silmitasertib 19,20 , and has a documented role in DNA damage response (reviewed in 21 ). We modeled the loss of CK2 kinase activity by knocking out catalytic subunit-encoding genes CSNK2A1 (α) and CSNK2A2 (α’).…”